Aerodynamic drag reducing apparatus

ABSTRACT

An aerodynamic drag reducing apparatus is adaptable for use with vehicles having downstream surfaces that are not streamlined. The apparatus consists of a series of nesting shapes and/or frameworks that extend rearward for use in a drag reducing configuration and collapse for use in a space saving configuration.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/694,865, filed Jun. 29, 2005, U.S. ProvisionalPatent Application Ser. No. 60/705,026, filed Aug. 2, 2005, and U.S.Provisional Patent Application Ser. No. 60/705,029, filed Aug. 3, 2005,which applications are hereby incorporated by reference in theirentirety.

FIELD OF THE INVENTION

The present invention relates to an aerodynamic drag reducing apparatusfor use with vehicles having downstream surfaces that are notstreamlined. Examples include: over-the-road trucks and truck trailers,vans and minivans, motor homes and travel trailers, and pickup trucks.In vehicles such as pickup trucks, one non-streamlined surface is nearthe center of the vehicle. The present invention is suitable for usewith vehicles having rear doors.

BACKGROUND OF THE INVENTION

It is known that a significant amount of aerodynamic drag is createdwhen a vehicle travels at typical velocities on a modern roadway. Thisis partly due to areas of low pressure that act on the rear surfaces ofthe vehicle. The low pressure becomes more pronounced as airflow overthe vehicle separates from the vehicle surfaces. The phenomenon ofairflow separation is also well known in the design of aircraft wingsand, in this case, causes the wing to stall.

Vehicles with blunt rear ends are especially affected by airflowseparation, often starting at the abrupt transition to the rear—nearvertical surface. The low pressure that the airflow separation causes iscompounded by the relatively large area that the low pressure acts overas compared with more streamlined vehicles.

The low air pressure acting on the rear surfaces of a moving vehicleproduces a force that resists the forward motion of the vehicle. Thisforce is opposed by the vehicle's engine and requires power that istypically produced by burning fuel. Any reduction in aerodynamic dragresults in a reduction in fuel consumption.

In a period of high fuel prices, increasing fuel efficiency is a growingconcern. Aerodynamic improvements are especially valuable since they canbe combined with other improvements such as engine efficiency andreduced chassis weight. Increasing fuel efficiency also provides thevaluable benefit of increasing the range a given vehicle can travelbetween refueling.

The present invention uses the technique of tapering the rear surfacesof a vehicle. The same technique is in use with other vehicles such asstreamlined cars and airplanes. It has also been applied toover-the-road trucks where it is known as a “boat-tail”.

BRIEF SUMMARY OF THE INVENTION

The present invention is concerned with providing an aerodynamic dragreducing apparatus, which reduces energy consumption as described above.More specifically, this is achieved by adding gently sloping surfacesdownstream of rear facing surfaces of the vehicle with the goal ofkeeping the airflow attached. Keeping the airflow attached results inless aerodynamic drag and reduced fuel consumption.

On certain vehicles, simply adding the required additional surfaceswould result in a substantial increase to the vehicle length. Thislength would be acceptable in many cases on the open road in uncongestedtraffic, but would be impractical in crowded urban roadways, parkinglots, campgrounds, and loading docks. To address this, the presentinvention has two primary configurations. The first is an extendedconfiguration that reduces drag and fuel consumption, especially athighway speeds. The second is a retracted configuration that providesmuch less, if any, drag reduction, but results in a vehicle that ispractical in crowded areas. This combination of configurations in thesame apparatus is especially useful since zones of higher speed drivingare often not congested. These high-speed zones are also where the dragreducing potential is the highest. Likewise, congested areas often havereduced speed with less drag reducing potential, but in these cases, theretracted configuration may be required for maneuvering in traffic.

In order to easily and conveniently convert between the retractedconfiguration and the extended configuration, the present inventionemploys shapes that nest. The largest such shape is either attached orclosest to the vehicle when the apparatus is in the extendedconfiguration. The shapes gradually become smaller as their position inthe extended configuration is farther from the vehicle. When extended,the collection of shapes either forms an enclosed or mostly enclosedvolume or provides a framework that can be covered by a fabric. In thelatter case, the combination of framework and fabric forms an enclosedor mostly enclosed volume.

A further objective of the present invention is to provide a mechanismto support the nested shapes while they are retracted, extended, and inany transitional position. If fabric is used, it is also supported bythe mechanism. This mechanism is comprised of a series of linkagesbetween successive nested shapes. In certain forms of the invention, thelinkages are spring-loaded which results in two stableconfigurations—fully extended and fully retracted. This feature aids inkeeping the apparatus in one of the two desired configurations. Thereare also features in the apparatus that prevent the various parts fromreaching an undesired configuration, such as over-extension.

An optional feature of the present invention provides a method ofmotorizing the extension and retraction. This allows for the remoteextension and retraction of the apparatus for convenience.

Another optional feature is covers that keep elements such as mud, snow,and ice from reaching and collecting on interior surfaces and parts ofthe apparatus.

To accommodate vehicles with rear doors, an optional feature of thepresent invention is to have the overall aerodynamic shape split intotwo halves. These halves can be opened, providing access to the reardoors of the vehicle. This optional feature requires a support panel orframework that holds the first nested shape and any optional motorizedextension and retraction mechanism. The support panel is mounted on ahinge, linkage, or linear slide. The framework can be moved away fromthe rear door(s) of the vehicle to allow access. Alternatively, the reardoor of the vehicle itself may be incorporated in the apparatus byserving as the support panel. An alternative to having the apparatus intwo halves would be to have a single whole apparatus mounted on asupport panel, door, or framework that is mounted on a hinge, linkage,or linear slide. In this case, the whole apparatus would be moved awayfrom the rear door(s) of the vehicle.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The benefits and advantages of the present invention will become morereadily apparent to those of ordinary skill in the relevant art afterreviewing the following detailed description and accompanying drawings,wherein:

FIGS. 1A through 1E show a basic form of the present invention mountedon the rear of an over-the-road trailer in various configurations. Inthis form, the aerodynamic drag reducing apparatus is in two halves,split right and left. The right and left halves are opened for access tothe rear of the trailer. In particular:

FIG. 1A is a perspective view from the left rear corner. Theconfiguration shown is fully extended with trailer doors closed.

FIG. 1B is a perspective view from the left rear corner. Theconfiguration shown is fully retracted with trailer doors closed.

FIG. 1C is a perspective view from the left rear corner. Theconfiguration shown is fully retracted on the left half and fullyextended on the right with both trailer doors closed.

FIG. 1D is a partial perspective view from the right rear corner. Theconfiguration shown is fully retracted on the left half and fullyextended on the right with both trailer doors opened.

FIG. 1E is a partial perspective view from the left rear corner. Theconfiguration shown is fully retracted on the left half and fullyextended on the right with both trailer doors opened.

FIG. 1F is a perspective view showing the right apparatus fullyretracted.

FIG. 1G is a partial perspective view from the left rear corner of thesame basic form mounted on the rear of an over-the-road trailer. Theconfiguration shown has both halves partially extended with the righttrailer door closed and the left trailer door open.

FIG. 1H is a perspective view showing the right apparatus partiallyextended.

FIG. 1I is a perspective view showing the right apparatus fullyextended.

FIGS. 2A through 2H show the linkage assembly and components. Thelinkage assemblies are used to hold the panel assemblies in place. Inparticular:

FIG. 2A is a perspective view showing the linkage assembly in its fullyextended position.

FIG. 2B is a second perspective view showing the linkage assembly in itsfully extended position.

FIG. 2C is a cross section of the linkage assembly showing the linkageassembly fully extended. The section cut is perpendicular to the linkagerotation axis and is shown in FIG. 2X.

FIG. 2D is a perspective view showing the linkage assembly in acollapsed position.

FIG. 2E is a cross section of the linkage assembly showing the linkageassembly in a collapsed position. The section cut is perpendicular tothe linkage rotation axis and is shown in FIG. 2X.

FIG. 2F is a perspective view showing the torsion spring component. Thespring, as installed, tends to move the linkage to a fully extendedconfiguration.

FIG. 2G is a perspective view showing the linkage component that mountstoward the interior of a panel assembly.

FIG. 2H is a perspective view showing the linkage component that mountstoward the upstream edge of a panel assembly.

FIG. 2X is a plan view of the linkage assembly. It also shows thesection cut used to create FIG. 2C and FIG. 2E.

FIGS. 3A through 3F show several variations of the basic panel assemblyand their features. These panel assembly variations are used together toform the basic apparatus. Each of the panel assemblies has provisions tomount several of the extension-retraction linkages mentioned above andare referred to as “linkage assemblies” when discussed below. Thesepanels, in fact, become part of that linkage chain in the overallapparatus. When relative placements are discussed below, they are inreference to the placements in a fully extended apparatus. In the formshown in these figures, the panel assemblies each have provisions toguide an extension-retraction web. The web exerts forces on the guidesthat cause the apparatus to extend and retract. In particular:

FIG. 3A is a perspective view showing the panel assembly farthestupstream. This panel assembly typically does not move during theextension and retraction of the apparatus. This panel assembly could befixedly mounted on the support panel or mounting framework. It hasprovisions to rotatably mount several linkage assemblies, which hold thenext panel assembly immediately downstream.

FIG. 3B is a perspective view showing a typical panel assemblyrepresentative of all panel assemblies in the basic apparatus with theexception of the farthest upstream and farthest downstream panelassemblies. These panel assemblies have provisions to rotatably mounttwo sets containing several linkage assemblies each. The first set ismounted toward the upstream edge of the panel assembly and is used tohold the linkage assembly that is also connected to the panel assemblyimmediately upstream. The second set is mounted in the interior of thepanel assembly and is used to hold the linkage assembly that is alsoconnected to the panel assembly immediately downstream. In thisparticular view, the two sets of mounts are at the same elevation. Inthe form shown, the panel assembly has notches to allow the upstreamlinkage assemblies to swing through their required range of motion. Thenotches, as shown here, are not visible from the exterior of theapparatus when it is fully deployed.

FIG. 3C is a perspective view showing a variation of the typical panelassembly discussed in the preceding paragraph. The variation illustratedlocates the upstream and downstream linkage mounts at different ratherthan the same elevation.

FIG. 3D is a perspective view showing the panel assembly farthestdownstream. It has provisions to rotatably mount several linkageassemblies. Each of these linkage assemblies also attach to the panelassembly immediately upstream. In the form shown, this panel has anextension-retraction, web-guiding feature in addition to two webmounting features. The first web-mounting feature holds the end of theweb closest to the web guiding features in the panel assemblies. Thesecond web-mounting feature holds the end of the web closest to theextension-retraction actuation motor. In the form shown, this panelassembly has notches to allow the linkage assemblies to swing throughtheir required range of motion.

FIG. 3E is an enlarged partial perspective view of a typical panelassembly showing the pivoting linkage mounting surfaces and notchesmentioned above.

FIG. 3F is an enlarged partial section view of a typical panel assemblyshowing the linkage mounts, notches, and web guides mentioned above. Thesection cut is through the vertical center of the panel assembly and isshown in FIG. 3X.

FIG. 3X is an elevation view showing the interior of a typical panelassembly. It also shows the section cut used to create FIG. 3F.

FIGS. 4A through 4C show the extension-retraction web, its routing,related hardware, and attachment points. In particular:

FIG. 4A is a partial perspective view showing the web, theextension-retraction drive motor and pulley, the web corner pulley, andweb-to-panel attachment points. The method of retracting the apparatussimply involves shortening the length of the longest straight section ofweb that attaches farthest downstream on the farthest downstream panelassembly.

FIG. 4B is a section view of a typical basic partially extendedapparatus showing different configurations of link assemblies, theextension-retraction web routing, the web attachment points and webpulleys. It also shows a linkage extending past the usual boundary ofthe apparatus half. The section cut is through the vertical center of atypical apparatus and is shown in FIG. 4X.

FIG. 4C is a reduced scale version of FIG. 4B showing only the web andthe centers of the web pulleys and centers of the panel web guides. Thesection cut is through the vertical center of a typical apparatus and isshown in FIG. 4X.

FIG. 4X is an elevation view showing the interior of the apparatus. Italso shows the section cut used to create FIGS. 4B and 4C.

FIG. 5 is a partial section view showing two linkage assemblies from endto end. The first linkage assembly is between a fully retracted pair ofpanel assemblies. The second linkage assembly is between a fullyextended pair of panel assemblies. In both cases, the linkage assembliesthemselves are fully extended. Since the linkage assemblies arespring-loaded to seek this fully extended configuration, the apparatuswill seek either the extended or retracted configurations between eachset of neighboring panels. The linkage assemblies also form a mechanicalstop to keep the apparatus from over extending or over retracting,holding each pair of neighboring panels either in the extended orretracted position. This is very desirable since those twoconfigurations are sought in operation, and movement drifting toward anintermediate position would either lose aerodynamic performance, ifdrifting from the extended configuration, or occupy more volume, ifdrifting from the retracted position. The view's section cut is takenthrough the linkage component that attaches to the upstream edge of thepanel assemblies and is perpendicular to the pivot point within thelinkage assembly. The section cut is shown in FIG. 5X.

FIG. 5X is an elevation view showing the interior of a typical panelassembly. It also shows the section cut used to create FIG. 5.

FIGS. 6A and 6B illustrate the methods used to keep the various linkageassemblies from interfering with each other when transitioning betweenthe extended and retracted configurations. In particular:

FIG. 6A is a perspective view showing the smallest, most crowded twosets of panel assemblies, located farthest downstream and illustratesthat staggering the elevation of the linkage assemblies lets each passthrough the center plane without interfering with the opposing linkageassembly. It also shows that interference can be avoided by placinglinks that run in a horizontal plane lower than the operating range oflinks that run in a vertical plane.

FIG. 6B is a partial perspective view showing two sets of adjacent panelassemblies and illustrates that interference can be avoided by placinglinks that run in a vertical plane farther inboard than the operatingrange of links that run in a horizontal plane.

FIGS. 7A and 7B show a basic form of the present invention with theaddition of vortex generators. In particular:

FIG. 7A is a partial perspective view showing a typical panel assemblywith vortex generators attached.

FIG. 7B is a partial perspective view of fully extended right and lefthand apparatuses with vortex generators attached. The apparatuses aremounted on an over-the-road trailer. The view is from the right rearcorner of the trailer.

FIGS. 8A through 8D show an extended height form of the presentinvention mounted on the rear of an over-the-road trailer in variousconfigurations. In this form, the aerodynamic drag reducing apparatus isin two halves, split right and left. The right and left halves areopened for access to the rear of the trailer. In addition, trailerskirts are shown. In particular:

FIG. 8A is a perspective view from the left rear corner. Theconfiguration shown is fully extended with trailer doors closed.

FIG. 8B is a perspective view from the left rear corner. Theconfiguration shown is fully retracted with trailer doors closed.

FIG. 8C is a perspective view from the left rear corner. Theconfiguration shown has the left apparatus fully retracted and rightapparatus fully extended and both trailer doors open.

FIG. 8D is a perspective view showing the right rear underside corner ofthe trailer. The configuration shown has the left apparatus fullyretracted and right apparatus fully extended and both trailer doorsopen.

FIGS. 9A through 9D show a truncated length form of the presentinvention mounted on the rear of an over-the-road trailer in variousconfigurations. In this form, the aerodynamic drag reducing apparatus isin two halves, split right and left. The right and left halves can beopened for access to the rear of the trailer. In particular:

FIG. 9A is a perspective view from the left rear corner. Theconfiguration shown is fully extended with trailer doors closed.

FIG. 9B is a perspective view from the left rear corner. Theconfiguration shown is fully retracted with trailer doors closed.

FIG. 9C is a perspective view from the left rear corner. Theconfiguration shown has the left apparatus fully retracted and the rightapparatus fully extended and both trailer doors closed.

FIG. 9D is a perspective view showing the right rear corner. Theconfiguration shown has the left apparatus fully retracted and rightapparatus fully extended and both trailer doors open.

FIGS. 10A through 10E show a form of the present invention with linearsliding joints forming a connection between neighboring panel assemblieson the right and left lower horizontal panels. Linkage assemblies asdescribed above connect the right and left upper sloping panels and bothvertical panels. In this form, the aerodynamic drag reducing apparatusis in two halves, split right and left. The right and left halves areshown mounted to the rear of an over-the-road trailer in variousconfigurations. The right and left halves can be opened for access tothe rear of the trailer. The extension-retraction web and its relatedfeatures are not shown, but could be included as described above. Inparticular:

FIG. 10A is a perspective view from the left rear corner. Theconfiguration shown is fully extended with trailer doors closed.

FIG. 10B is a perspective view from the left rear corner. Theconfiguration shown is fully retracted with trailer doors closed.

FIG. 10C is a perspective view from the left rear corner. Theconfiguration shown has the left apparatus fully retracted and rightapparatus fully extended and both trailer doors closed.

FIG. 10D is a perspective view showing the right rear corner. Theconfiguration shown has the left apparatus fully retracted and rightapparatus fully extended and both trailer doors open.

FIG. 10E is an enlarged partial perspective view from the left rearcorner. The configuration shown has the left apparatus fully retractedand right apparatus fully extended and both trailer doors closed. Thedetails of the linear sliding joints are visible.

FIG. 10F is an enlarged partial rear elevation view on a typical panelassembly used in the preceding paragraphs. The details of the separatehalves of the linear joint are visible.

FIG. 10G is an enlarged partial perspective view of the left half of theabove apparatus. The view is from the rear underside slightly left ofcenter. The details of the linear sliding joints are visible.

FIGS. 11A through 11C show a form of the present invention mounted onthe rear of a minivan in various configurations. In this form, theaerodynamic drag reducing apparatus is in two halves, split right andleft. An aerodynamic fairing is also used to fill the gap between thenon-planar rear of the vehicle and the apparatus. The right and lefthalves can be opened for access to the rear of the vehicle. These threeperspective views are taken from the left rear corner of the vehicle andare shown with access to the rear doors of the minivan closed. Theextension-retraction web and its related features are not shown butcould be included as described above. In particular:

FIG. 11A shows both halves fully extended.

FIG. 11B shows both halves fully retracted.

FIG. 11C shows the left apparatus fully retracted and right apparatusfully extended.

FIG. 11D is a partial perspective view of the interior of the rightapparatus in the fully extended configuration. This view illustratesthat the nesting shapes from one panel assembly to another do notnecessarily need to be similar in shape. It also illustrates that atransition in the basic shape can be made from one nesting shape to theadjacent nesting shape.

FIG. 11E is a perspective view of the aerodynamic fairing. In this view,the fairing is shown as one piece. It could also be made of two halves.In this case, each half could be mounted to the apparatus supportstructure. This would allow each fairing half to open with itsrespective apparatus half and would allow greater access to the rear ofthe vehicle. The fairing also contributes to the reduction inaerodynamic drag.

FIG. 11F is a side elevation view of a minivan with the aerodynamicapparatus mentioned above mounted on its rear fully extended. A fairingsmoothly covers the gap between the drag reducing apparatuses and theminivan.

FIG. 11G is a perspective view showing the interior of the rightapparatus in the fully extended configuration.

FIG. 11H is a perspective view of a typical panel assembly of the formused in the preceding paragraphs. It is shown with two sets of linkagemounting features and notches. These features are identical in purposeto those shown in FIGS. 3B and 3C. The essential difference is only thepanel shape.

FIG. 11I is a perspective view showing the panel assembly farthestupstream. With the exception of the shape, this panel assembly sharesthe same features with the same purpose as the panel assembly shown inFIG. 3A.

FIGS. 12A through 12C show a form of the present invention mountedbehind the passenger cab of a pickup truck in two configurations. Inthis form, the aerodynamic drag reducing apparatus extends and retractsas a single mechanism. In this form, the apparatus, when fully extended,covers a pocket in the vehicle producing an overall aerodynamic shapethat significantly reduces drag. In this form, two sets of linearsliding joints are used, each at a different location, between adjacentpanel assemblies. A linear sliding joint is also formed between thebottom surfaces of the apparatus and the top surfaces of the pickup boxsides. The interior of the pickup truck box can be accessed byretracting the apparatus. A retracted apparatus allows rear visibilitythrough the apparatus and serves as a sun-shielding louver as well. Theextension-retraction web and its related features are not shown butcould be included as described above. In particular:

FIG. 12A is a perspective view from the left rear corner. Theconfiguration shown is fully extended.

FIG. 12B is a perspective view from the left rear corner. Theconfiguration shown is fully retracted.

FIG. 12C is a rear elevation view. The configuration shown is fullyextended. This figure illustrates that the surfaces of the panelassemblies do not need to be perpendicular or parallel to each other.

FIGS. 12D and 12E show the apparatus in a form suitable for mountingbehind a pickup truck passenger cab. In particular:

FIG. 12D is a perspective view showing the interior of the apparatus ina fully extended configuration. The linkage assemblies shown in thisform are optional and serve the purpose of driving each adjacent pair ofpanels into either the retracted or extended configuration as mentionedabove in the discussion on FIG. 5. The linkage assembly also forms atravel-stop preventing over extension and over retraction. A pair oflinkage assemblies and a connection between them also coordinates themovement between the right and left sides and reduces the chance ofbinding.

FIG. 12E is an enlarged partial front elevation view showing about halfof the aerodynamic drag reducing apparatus. The half shown here ismirrored somewhere near the cutting curve. This view together with FIG.12C illustrates that linear sliding surfaces between adjacent panelassemblies can be implemented on more than one side of such anapparatus.

FIG. 12F is a perspective view of two extension-retraction linkageassemblies with a straight shaft connection joining a corresponding pairof links together. This ensures coordinated, non-binding action on allforms of the apparatus, especially where the spacing between linkageassemblies is wide. The straight shaft connection shown in this viewcould be replaced with a flexible shaft connection in the case that thecoordinated links do not share a common pivot centerline. A gear trainconnection including components such as U-joints, belts, pulleys, andbevel gears could also replace the straight shaft connection. This viewshows two linkage assemblies being connected and therefore coordinated.Additional linkage assemblies could be added in series or in parallel.In this view, linkage assemblies from between the same panel assembliesare connected. Linkage assemblies that are not between the same panelassemblies could also be connected in series or in parallel. An actuatorcontrolling multiple linkage assemblies could be added to the shaft oralternate connecting parts mentioned above.

FIGS. 12G through 12I are perspective views showing panel assembliesused in a form of the apparatus suitable for mounting behind a pickuptruck passenger cab. When relative placements are discussed below, theyare in reference to the placements in a fully extended apparatus. Inparticular:

FIG. 12G shows the panel assembly mounted farthest upstream. It showslinkage attachment points and linear sliding joints.

FIG. 12H shows a typical panel assembly—a plurality of which are used indifferent sizes between the panel assemblies farthest upstream andfarthest downstream. It shows linkage attachment points, linear slidingjoints, and notches. The notches allow the linkage assemblies to movethrough their range of motion. The notches, as shown here, are notvisible from the exterior of the apparatus when it is fully deployed.

FIG. 12I shows the panel assembly mounted farthest downstream. It showslinkage attachment points, linear sliding joints, and notches. Thepurpose of the notches is the same as discussed in the precedingparagraph.

FIG. 13A shows a side elevation view of a typical over-the-road tankertruck.

FIGS. 13B through 13F show a form of the present invention suitable formounting behind an over-the-road tanker truck. In this form, theaerodynamic drag reducing apparatus extends and retracts as a singlemechanism. An aerodynamic fairing is also used to fill the gap betweenthe non-planar rear of the vehicle and the apparatus. Theextension-retraction web and its related features are not shown butcould be included as described above. In particular:

FIGS. 13B and 13C are perspective views from the left rear corner of thetanker trailer. In particular:

FIG. 13B shows the apparatus fully extended.

FIG. 13C shows the apparatus fully retracted.

FIGS. 13D through 13F are partial section views. The views' section cutis taken through the vertical and longitudinal plane of symmetry of thetanker trailer. The section cut is shown in FIG. 13X. In particular:

FIG. 13D shows the apparatus fully extended.

FIG. 13E shows the apparatus fully retracted.

FIG. 13F shows the apparatus partially extended.

FIGS. 13G through 13J are perspective views showing primarily theinterior of the apparatus and its components. The views show theapparatus and its components in a form suitable for mounting behind anover-the-road tanker truck. When relative placements are discussedbelow, they are in reference to the placements in a fully extendedapparatus. In particular:

FIG. 13G shows the apparatus in a fully extended configuration.

FIG. 13 H shows the panel assembly farthest downstream. Also shown arethe linkage attachment points and linkage clearance notches.

FIG. 13I shows a typical panel assembly—a plurality of which are used indifferent sizes between the panel assemblies farthest upstream andfarthest downstream. It shows linkage attachment points, notches, andgrooves. The notches allow the linkage assemblies to move through theirrange of motion. The notches, as shown here, are not visible from theexterior of the apparatus when it is fully deployed. In addition to thenotches going through the panel on its upstream edge, shallow groovesare shown on the interior surfaces. These shallow grooves allow spacefor the linkage assemblies to occupy when the apparatus is in itsretracted configuration.

FIG. 13J shows the apparatus in a fully retracted configuration.

FIG. 13K is a perspective view showing an aerodynamic fairing in a formsuitable for use between an over-the-road tanker truck and the apparatusdiscussed in the preceding paragraphs.

FIG. 13X is a bottom plan view of the apparatus and aerodynamic fairingmentioned in the preceding paragraphs. It also shows the section cutused to create FIG. 13D through 13F.

FIGS. 14A through 14K and FIG. 14X show a variation of the basic form ofthe present invention. When relative placements are discussed below,they are in reference to the placements in a fully extended apparatus.The present variation incorporates a smooth transition across theapparatus and the vehicle or trailer. The smooth transition, as shown inthese figures, is formed into the panel assembly farthest upstream. Thecomponents and their functions are similar or identical to the basicform as shown in FIGS. 1A through 1I, FIGS. 3A through 3F, FIG. 5, andFIGS. 6A and 6B. As in the basic form, the aerodynamic drag reducingapparatus is in two halves, split right and left. The right and lefthalves are opened for access to the rear of the trailer. The slightchanges required by this variation are further described below. Inparticular:

FIGS. 14A through 14C show a variation of the basic form of the presentinvention mounted on the rear of an over-the-road trailer in twoconfigurations. In particular:

FIG. 14A is a partial perspective view from the left rear corner. Theconfiguration shown is fully extended with trailer doors closed.

FIG. 14B is a partial perspective view from the left rear corner. Theconfiguration shown is fully retracted with trailer doors closed.

FIG. 14C is a partial side elevation view from the left. Theconfiguration shown is fully retracted with trailer doors closed andillustrates the smooth transition across the trailer and apparatus.

FIG. 14D is a perspective view showing the right apparatus fullyretracted. It is similar to FIG. 1F with the exception of the panelassembly farthest upstream. This panel assembly has curved surfaces thatare tangent to their corresponding exterior trailer surfaces.

FIG. 14E is a partial section view of a partially extended apparatus. Itis similar to FIG. 4B with the exception of the panel assembly farthestupstream, a special set of more compact extension-retraction linkageassemblies, a slightly different web corner pulley location, and aslightly different apparatus extension configuration. The linkageassemblies between the panel assembly farthest upstream and the adjacentpanel assembly are specially designed to fit into the more compact spaceavailable when this form of the apparatus is in the retractedconfiguration. The section cut is through the vertical center of theapparatus and is shown in FIG. 14X.

FIG. 14F is a perspective view showing the panel assembly farthestupstream. It is similar to the panel assembly shown in FIG. 3A with theexception of the curved surfaces.

FIG. 14G is a partial section view of a partially extended apparatus. Itis similar to FIG. 14E with the exception of a different apparatusextension configuration. The more compact linkage assembly mentionedabove is shown at its closest point to the second farthest upstreampanel assembly. Small notches were added to this panel assembly to allowthe more compact linkage assemblies to swing through their requiredrange of motion. The small notches are not visible from the exterior ofthe apparatus when it is fully deployed. The section cut is through thevertical center of the apparatus and is shown in FIG. 14X.

FIG. 14H is a perspective view showing the more compact linkage assemblyin its fully extended position. This linkage has the same spacingbetween its rotational mounts when fully extended as the less compactlinkage shown in FIGS. 2A and 2B. It also has the same collapsing range.It could therefore replace the less compact linkage if small notches, asmentioned above, were added to the upstream edge of the remaining panelassemblies.

FIG. 14I is a cross section of the more compact linkage assembly showingthe linkage assembly fully extended. The section cut is perpendicular tothe linkage rotation axis and is similar to section cut shown in FIG.2X.

FIG. 14J is an enlarged partial perspective view of the exterior and theupstream edge of the second farthest upstream panel assembly. Thelinkage pivoting surfaces near the upstream edge, the former notches,and the added shallow notches are shown.

FIG. 14K is an enlarged partial section view of a partially extendedapparatus. It is similar to FIG. 14E with the exception of a differentapparatus extension configuration. The more compact linkage assemblymentioned above is shown at its closest point to the farthest upstreampanel assembly. This view also illustrates the extension-retraction webrouting between panel assemblies. If the web were drawn tighter in theareas shown in this view, the upstream edge of the downstream panelassemblies would be drawn towards the adjacent downstream edge of theupstream panel assemblies. This would have the cumulative effect ofextending the apparatus. The section cut is through the vertical centerof the apparatus and is shown in FIG. 14X.

FIG. 14X is an elevation view showing the interior of the apparatus. Italso shows the section cut used to create FIGS. 14E, 14G, and 14K.

FIGS. 15A through 15L show an optional configuration consisting ofcovers added to the basic configuration. The covers serve two purposes.The first purpose is to cover the openings that expose the interiorportions of the apparatus when it is in the fully retractedconfiguration. This is a valuable feature in that it keeps elements suchas dirt, mud, snow, and ice from reaching and accumulating in theinterior of the apparatus. At a certain amount, accumulations of suchelements could interfere with the proper operation of the apparatus. Thesecond purpose served by these covers is providing a smoother transitionfrom the edge of one panel assembly to the panel assembly immediatelydownstream. With the exception of these covers and their related hingelines, the components and their functions are identical to the basicform as shown in FIGS. 1A through 1I, FIGS. 3A through 3F, FIG. 5, andFIGS. 6A and 6B. As in the basic form, the aerodynamic drag reducingapparatus is in two halves, split right and left. The right and lefthalves open for access to the rear of the trailer. The slight changesrequired by these optional doors are further described below. Inparticular:

FIG. 15A is a partial perspective view from the left rear corner. Theconfiguration shown is fully extended with trailer doors closed. Theoptional covers are shown laying flat over the panel assemblyimmediately downstream.

FIG. 15B is a partial perspective view from the left rear corner. Theconfiguration shown is fully retracted with trailer doors closed. Theoptional covers are shown with their interior surfaces laying nearvertical and covering the opening that would otherwise be there.

FIG. 15C is a perspective view showing the right apparatus fullyextended. It is identical to FIG. 1I with the exception of the covers.

FIG. 15D is an enlarged partial elevation view showing the interior ofthe right apparatus. This view illustrates the partial smoothing thecovers provide over the joints between the panel assemblies. In theapparatus as shown, the panel assembly farthest downstream when theapparatus is fully extended is also shorter than the others in thedownstream direction. This view illustrates that a smaller cover is usedto cover the joint in front of the short panel.

FIG. 15E is a partial elevation showing the interior of the rightapparatus in a partially extended configuration. The view shows panelassemblies that are fully extended, partially extended, and fullyretracted with respect to their immediate neighbor. The view also showsthe covers in contact with the panel assembly immediately downstream.This view illustrates that the covers could be actuated by a simpletorsional spring along their hinge line. As the apparatus extends, thepanel assemblies will push the covers into their open position. As theapparatus retracts, the torsional springs will return the covers overthe openings.

FIG. 15F is a partial perspective view showing the exterior of the leftapparatus. The apparatus extension configuration is the same as thatshown in FIG. 15E. This view illustrates that unless fully extended orretracted, an opening remains at the exterior corners of the apparatus.

FIGS. 15G through 15I are perspective views showing the interior of atypical panel assembly with typical covers installed. With the exceptionof the covers and their related hinge lines, the panel assemblies haveidentical features and functions as those shown in FIGS. 3B and 3C. Inparticular:

FIG. 15G shows the covers in a configuration where the apparatus isfully extended.

FIG. 15H shows the covers in a configuration where the apparatus ispartially extended.

FIG. 15I shows the covers in a configuration where the apparatus isfully retracted.

FIG. 15J is a partial perspective view showing interior surfaces of atypical panel assembly and the cover hinge lines.

FIG. 15K is a perspective view of a cover showing the hinge line thatconnects it to the panel assemblies. This cover is typical of thoserunning in a vertical direction in the form of the apparatus shown here.Both ends of this cover meet adjacent covers that have hinge lines thatare not collinear with its own. The ends of this cover meet the ends ofthe adjacent covers only in the closed position. The ends of this coverare cut to whatever angle is needed to match the adjacent covers in theretracted configuration of the apparatus.

FIG. 15L is a perspective view of a cover showing the hinge line thatconnects it to the panel assemblies. This cover is typical of thoserunning in a horizontal direction in the form of the apparatus shownhere. One end of this cover meets another cover with a hinge linecollinear to its own. This end is cut perpendicular to the hinge line.The opposite end of this cover meets another cover only in the closedposition. This end of this cover is cut to whatever angle is needed tomatch the adjacent cover in the retracted configuration of theapparatus.

FIGS. 16A through 16Q show a form of the present invention that iscompletely smooth on its exterior surface when the apparatus is in theextended configuration. This form employs a panel in the farthestupstream position similar to that shown in FIGS. 14A through 14G. Itlikewise uses a set of compact linkage assemblies as shown in FIG. 14H.This form also uses covers similar to those shown in FIGS. 15A through15I. In addition to these covers, corner covers are used to formcompletely smooth exterior corners when the apparatus is in the extendedconfiguration. In addition to the features above, each panel assemblyhas an exterior surface that is shaped to blend in with the covers toform a completely smooth exterior surface when the apparatus is in theextended position. The covers with the exception of the corner coversalso keep the elements from reaching the interior of the apparatus. Asin the basic form, the aerodynamic drag reducing apparatus is in twohalves, split right and left. The right and left halves open for accessto the rear of the trailer. The modifications to the basic form requiredby the present form are further described below. In particular:

FIGS. 16A through 16C show the apparatus mounted on the rear of anover-the-road trailer in the fully extended configuration. Inparticular:

FIG. 16A is a partial top plan view illustrating completely smoothexterior sides of the apparatus.

FIG. 16B is a partial elevation view from the left illustrating thecompletely smooth top and bottom of the apparatus.

FIG. 16C is a partial perspective view from the left rear corner. Itillustrates the completely smooth corner edges.

FIG. 16D is a perspective view showing the interior and rear of the lefthand apparatus in a retracted configuration. The non-corner covers areshown lying with their interior surfaces on a vertical plane. The cornercovers are showing protruding beyond the rest of the apparatus.

FIGS. 16E through 16G (and FIGS. 16I and 16J) show the left handapparatus in the same partially extended configuration. In particular:

FIG. 16E is a perspective view showing the interior of the apparatus.

FIG. 16F is a perspective view showing the exterior of the apparatus.

FIG. 16G is the same view as FIG. 16F, but with the corner coversremoved.

FIG. 16H is a partial side elevation view showing the interior of theleft hand apparatus. This view illustrates an exterior panel assemblyand cover shape that results in the overall apparatus having acompletely smooth exterior shape when fully deployed.

FIGS. 16I and 16J (and FIGS. 16E through 16G) show the left handapparatus in the same partially extended configuration. In particular:

FIG. 16I is a partial side elevation view showing the interior of theleft hand apparatus.

FIG. 16J is the same view as FIG. 16I, but with the corner coversremoved.

FIGS. 16K through 16M are perspective views showing a typical panelassembly with typical covers installed. The views are similar to FIGS.15G through 15I with the addition of corner covers and specially shapedexterior surfaces on the panel assemblies. In particular:

FIG. 16K shows the covers in a configuration where the apparatus isfully extended.

FIG. 16L shows the covers in a configuration where the apparatus ispartially extended.

FIG. 16M shows the covers in a configuration where the apparatus isfully retracted.

FIG. 16N is a partial perspective view showing interior surfaces of atypical panel assembly and the cover hinge lines.

FIG. 16O is a perspective view of a cover showing the hinge line thatconnects it to the panel assemblies. This cover shares the same featuresand functions as the cover shown in FIG. 15K with the exception of aslightly different cross sectional shape and additional hinge lines toconnect to the corner covers.

FIG. 16P is a perspective view of a cover showing the hinge line thatconnects it to the panel assemblies. This cover shares the same featuresand functions as the cover shown in FIG. 15L with the exception of aslightly different cross sectional shape and additional hinge lines toconnect to the corner covers.

FIG. 16Q is a perspective view showing the interior surface of a typicalcorner cover and the hinge lines that connect it with the non-cornercovers mentioned in the preceding two paragraphs.

FIGS. 17A and 17B show the present invention in its basic form using ahinged opening to gain access to the rear of the vehicle or trailer. Inparticular:

FIG. 17A is a partial perspective view from the left rear corner showingthe apparatus on the back of an over-the-road trailer. The configurationshown has the apparatus fully retracted with the doors closed.

FIG. 17B is a partial perspective view from the right rear cornershowing the apparatus on the back of an over-the-road trailer. Theconfiguration shown has the apparatus fully retracted on the left doorand fully extended on the right door. The doors are both open.

FIGS. 18A and 18B show the present invention in its basic form usingtelescoping linear slides to move the doors sideways in order to provideaccess to the rear opening of the trailer. Both views show the apparatusmounted on the rear of an over-the-road trailer with the apparatus fullyretracted. In particular:

FIG. 18A is a partial perspective view from the left rear corner showingboth doors closed.

FIG. 18B is a partial perspective view from the right rear cornershowing both doors opened.

FIG. 18C is an enlarged partial perspective view from the direction ofthe trailer looking rearward. The view shows two of the apparatuses in abasic form mounted to a telescoping linear rail. The configuration shownhas both apparatuses fully retracted and both doors open.

FIGS. 19A through 19G show the present invention in its basic formmounted to the rear of an over-the-road trailer. In these views anarticulated linkage is used to open the doors and gain access to therear opening of the trailer. In particular:

FIG. 19A is a partial perspective view from the left rear corner. Theconfiguration shown is the apparatuses fully retracted and the doorsclosed.

FIG. 19B is a partial perspective view from the upper left rear corner.The configuration shown is the left apparatus fully retracted and theright apparatus fully extended. Both doors are fully opened.

FIGS. 19C through 19G are top plan views illustrating the action of thearticulated linkage. The configuration shown is the right apparatusfully extended and the left apparatus fully retracted. In particular:

FIG. 19C shows the doors fully closed.

FIG. 19D shows the doors partially opened.

FIG. 19E shows the doors opened farther than in FIG. 19D.

FIG. 19F shows the doors opened farther than in FIG. 19E.

FIG. 19G shows the doors fully opened.

FIGS. 20A through 20E show a form of the present invention thatsubstitutes hinged panels for the linkage assemblies such as those shownin FIGS. 2A and 2B. The notches on the leading edge of the panelassemblies have also been removed. Instead of the notches, the entireupstream edge of the panel assembly has been trimmed, allowing thehinged panels connecting to the upstream panel assembly to occupy asmall space in front of the upstream edge. In comparison, this reducesthe overlap from one panel assembly to the next when fully deployed. Thehinged panel assemblies are used on the top, bottom, right, and leftsides. The five figures are all partial elevation views showing theinterior of the left hand apparatus. The figures all show the highesthinged panel assembly in the fully retracted configuration and thelowest hinged panel assembly in the fully extended configuration. Aswith the linkage assemblies, the hinged panel assemblies could usesprings and hinge stops to keep the apparatus stable in the fullyextended and fully retracted positions. This form of the invention willallow a similar web extension-retraction system, providing the hingedpanels assemblies are interrupted to allow the web to pass through. Theterm “hinged panels” is used for descriptive purposes. In fact, the“hinged panels” are linkage assemblies in their own right. The hingedpanels could range in length from rather short to close to the length ofthe corresponding panel assembly. The minimum workable length for eachsuccessive group of hinged panels is determined by strengthconsiderations. The maximum workable length is determined by the need toavoid interference with the panel assemblies in all configurations. Inparticular:

FIG. 20A shows the center hinged panel assembly in the fully retractedconfiguration.

FIG. 20B shows the center hinged panel assembly in the slightly extendedconfiguration.

FIG. 20C shows the center hinged panel assembly extended farther than inFIG. 20B.

FIG. 20D shows the center hinged panel assembly extended farther than inFIG. 20C.

FIG. 20E shows the center hinged panel assembly fully extendedconfiguration.

FIGS. 21A through 21O show a form of the present invention that iscompletely smooth on its exterior surface when the apparatus is in theextended configuration. The present form incorporates a smoothtransition across the apparatus and the vehicle or trailer similar to,but more gradual than, those shown in FIGS. 14A through 14G and FIGS.16A through 16J. This form also uses covers similar to those shown inFIGS. 15A through 15I and FIGS. 16A through 16M. Furthermore, this formincorporates corner covers similar in purpose to those shown in FIGS.16A through 16F, but hinging on the panel assemblies rather than thehorizontal and vertical covers. The gradual transition from the vehiclesurfaces occurs over several of the farthest upstream panel assembliesand results in the panel assemblies being closer to each other. As thetransition is made more gradual, the affected panels become closer toeach other. At some point, practical linkage assemblies cannot be madecompact enough to fit in-between the panel assemblies in the retractedconfiguration. This form of the invention addresses this limitation byreplacing the affected linkage assemblies with those shown in thefigures below. As in the basic form, the aerodynamic drag reducingapparatus is in two halves, split right and left. The right and lefthalves open for access to the rear of the trailer. The modifications tothe basic form required by the present form are further described below.In particular:

FIGS. 21A through 21D show the apparatus mounted on the rear of anover-the-road trailer. In particular:

FIG. 21A is a perspective view from the left rear corner. Theconfiguration shown is fully extended with trailer doors closed.

FIG. 21B is a perspective view from the left rear corner. Theconfiguration shown is fully retracted with trailer doors closed.

FIG. 21C is a perspective view from the left rear corner. Theconfiguration shown is fully retracted with trailer doors opened.

FIG. 21D is an enlarged partial elevation view from the leftillustrating the completely smooth and gradually transitioning top andbottom of the apparatus.

FIG. 21E is a side elevation view showing the interior of the right handapparatus. This view illustrates an exterior panel assembly andhorizontal cover shape that results in the overall apparatus having acompletely smooth exterior shape when fully deployed. The shape of thevertical features of the panel assembly and the shape of the verticalcover, although not shown, are similar to those shown here.

FIG. 21F is a top plan view of the right hand apparatus illustrating thecompletely smooth and gradually transitioning exterior sides of theapparatus.

FIGS. 21G through 21I show the right hand apparatus in the samepartially extended configuration. In particular:

FIG. 21G is a side elevation view showing the interior of the apparatus.

FIG. 21H is a perspective view showing the interior, rear, and top ofthe apparatus.

FIG. 21I is a perspective view showing the exterior of the apparatusfrom the top, right, and rear.

FIGS. 21J through 21N show the right hand apparatus in the same fullyretracted configuration. In particular:

FIG. 21J is a side elevation view showing the interior of the apparatus.

FIG. 21K is a perspective view showing the interior, rear, and top ofthe apparatus.

FIG. 21L is a perspective view showing the exterior of the apparatusfrom the top, right, and rear.

FIG. 21M is a perspective view showing the interior of the apparatus.The trailer door has been removed in this view to show more fully theinterior features. The view is from the front, top, and left.

FIG. 21N is an enlarged partial perspective view showing the interior ofthe apparatus. The trailer door has been removed in this view to showmore fully the interior features. The view's perspective is the same asthat of FIG. 21M.

FIG. 21O is an enlarged partial perspective view showing the interior ofthe apparatus. The trailer door has been removed in this view to showmore fully the interior features. The apparatus is in a partiallyextended configuration. The view's perspective is the same as that ofFIG. 21N.

FIGS. 22A through 22E show the linkage assemblies and their componentsfirst introduced in FIG. 21E. These linkage assemblies are used to holdthe second and third panel assemblies in place. In particular:

FIG. 22A is a perspective view of the first linkage assembly in apartially extended configuration.

FIG. 22B is a perspective view of the second linkage assembly in apartially extended configuration.

FIG. 22C is a perspective view of the longer link of the first linkageassembly. The pocket serving as a travel stop is illustrated.

FIG. 22D is a perspective view of the shorter link of the first linkageassembly. The protrusion serving as a travel stop is illustrated.

FIG. 22E is an enlarged partial perspective view showing the travel stopprotrusion and travel stop pocket typical in the above two linkageassemblies. The joint is in a partially extended configuration.

FIGS. 23A through 23D show several variations of the panel assembliesfirst introduced in FIG. 21A. These panel assemblies are similar tothose shown in FIGS. 3A through 3E except as noted. In particular:

FIG. 23A is a perspective view showing a panel assembly similar to thoseshown in FIGS. 3B, 3C, and 15J. The present panel assembly differs inthat it has rounded corners and protrusions for mounting the cornercover described below. The panel assembly includes hinge lines forhorizontal and vertical covers.

FIG. 23B is a perspective view showing the panel assembly farthestdownstream. It is similar to the one shown in FIG. 3D except for theaddition of rounded surfaces.

FIG. 23C is a perspective view showing the panel assembly next to theone farthest upstream. It is different from the one shown in FIG. 23A inthat it only mounts to the linkage assemblies at its upstream edge. Thisalso means it is not a part of the linkage chain as discussed earlier,but merely mounts to the joint that is common to both linkage assembliesshown in FIGS. 22A and 22B. It is also different in that it has curvedexterior surfaces that are part of the smooth transition to the trailer.The panel assembly includes hinge lines for horizontal, vertical, andcorner covers.

FIG. 23D is a perspective view showing the panel assembly farthestupstream. It is similar to those shown in FIGS. 3A, 11I, and 14F exceptthat the linkage attachment point is near its upstream edge. It is alsodifferent in that it has exterior surfaces with compound curvature.Furthermore, hinge attachments are added near the trailing edge for usewith the horizontal, vertical, and corner covers.

FIGS. 23E through 23G show perspective views of typical covers firstintroduced in FIGS. 21A through 21O. Each cover has a single hinge lineconnecting it to the appropriate panel assembly. In particular:

FIG. 23E shows a horizontal cover similar to those shown in FIGS. 15Land 16P.

FIG. 23F shows a vertical cover similar to those shown in FIGS. 15K and16O.

FIG. 23G shows a corner cover.

FIG. 23H shows a partial perspective view of a typical corner cover asshown in FIG. 23G mounted to a typical panel assembly first introducedin FIGS. 21A through 21O. The configuration shown is near fullyretracted. The view is from the inside of the panel assembly lookingoutward.

FIGS. 24A through 24D illustrate a form of the present invention wherethe rigid components form only a framework and not an enclosed volumewhen fully extended. The aerodynamic shape is formed by fabric (notshown in these figures) which is attached to and takes its shape fromthe framework. All of the previously mentioned forms of the inventionmay be adapted to serve as a framework used in conjunction with fabric.A particular form with the apparatus split in two halves, right andleft, was chosen for the purpose of illustration. In particular:

FIGS. 24A and 24B are perspective views from the left rear cornershowing the present form of the drag reducing apparatus attached to anover-the-road trailer with the trailer doors closed. In particular:

FIG. 24A shows the apparatus fully extended. The fabric mentioned aboveis not shown. The fabric takes the form of a smooth surface joining theoutermost features of the framework. The exterior appearance of theapparatus with the fabric shown would be similar to FIG. 21A with theinternal features of the apparatus hidden by the fabric.

FIG. 24B shows the apparatus fully retracted. The fabric mentioned aboveis not shown. The fabric in this retracted configuration has the form ofa bellows, as shown in FIGS. 27F through 27H, attached to the trailingedges of the framework.

FIGS. 24C and 24D are perspective views showing the right hand apparatusin a fully extended configuration. The fabric mentioned above is notshown. The exterior appearance of the apparatus with the fabric shownwould be similar to FIGS. 21D and 21F. In particular:

FIG. 24C is a view from the left rear corner showing primarily theinside of the apparatus.

FIG. 24D is a view from the right rear corner showing primarily theoutside of the apparatus.

FIGS. 25A through 25D illustrate the component framework and panelassembly types which may be used in the present form of the invention.The combinations of types and their forms may be varied. The views arefrom the left rear corner of the components from the left handapparatus. In particular:

FIG. 25A shows the farthest upstream section as a panel assembly. Thisillustrates that panel assemblies and fabric covered frames may be mixedin the same apparatus.

FIG. 25B shows a framework whose leading edge, corners, and trailingedge define the adjacent shape of the apparatus.

FIG. 25C shows the farthest downstream section as a panel assembly.

FIG. 25D shows a framework whose trailing edge defines the adjacentshape of the apparatus.

FIGS. 26A through 26C all show the right hand apparatus in the samepartially extended configuration (also the same as shown in FIGS. 27Athrough 27E). The fabric has the form of a bellows attached to thetrailing edges of the framework as shown in FIGS. 27A through 27C. Inparticular:

FIG. 26A shows a partial side elevation view. The approximate shape ofthe fabric in relation to the rigid components is shown.

FIG. 26B shows primarily the interior of the apparatus from the leftrear corner. The fabric is not shown.

FIG. 26C shows primarily the exterior of the apparatus from the rightrear corner. The fabric is not shown.

FIGS. 26D through 26F all show the right hand apparatus in the samefully retracted configuration (also the same as shown in FIGS. 27Fthrough 27J). The fabric has the form of a bellows attached to thetrailing edges of the framework as shown in FIGS. 27F through 27H. Inparticular:

FIG. 26D shows a partial side elevation view. The approximate shape ofthe fabric in relation to the rigid components is shown.

FIG. 26E shows primarily the interior of the apparatus from the leftrear corner. The fabric is not shown.

FIG. 26F shows primarily the exterior of the apparatus from the rightrear corner. The fabric is not shown.

FIGS. 27A through 27E all show the right hand apparatus in the samepartially extended configuration that matches FIGS. 26A through 26C. Inparticular:

FIG. 27A through 27C show only the fabric. In particular:

FIG. 27A is shown in the same orientation as FIG. 26B.

FIG. 27B is an enlarged partial view with the same orientation as FIG.27A.

FIG. 27C is shown in the same orientation as FIG. 26C.

FIG. 27D shows the apparatus, complete with fabric, in the sameorientation as FIG. 26B.

FIG. 27E shows the apparatus, complete with fabric, in the sameorientation as

FIG. 26C.

FIGS. 27F through 27J all show the right hand apparatus in the samefully retracted configuration that matches FIGS. 26D through 26F. Inparticular:

FIG. 27F through 27H show only the fabric. In particular:

FIG. 27F is shown in the same orientation as FIG. 26E.

FIG. 27G is an enlarged partial view with the same orientation as FIG.27F.

FIG. 27H is shown in the same orientation as FIG. 26F.

FIG. 27I shows the apparatus, complete with fabric, in the sameorientation as FIG. 26E.

FIG. 27J shows the apparatus, complete with fabric, in the sameorientation as FIG. 26F.

DETAILED DESCRIPTION OF THE INVENTION

While the present invention is susceptible of embodiment in variousforms, there is shown in the drawings and will hereinafter be describeda presently preferred embodiment with the understanding that the presentdisclosure is to be considered an exemplification of the invention andis not intended to limit the invention to the specific embodimentillustrated.

The embodiment presented is also shown in various forms and shapes andwith various optional features in various combinations. These variationsalso are exemplifications of the invention and are not intended to limitthe combinations of forms, shapes, and optional features.

It should be further understood that the title of this section of thisspecification, namely, “Detailed Description of the Invention”, relatesto a requirement of the United States Patent Office, and does not imply,nor should be inferred to limit the subject matter disclosed herein.

Referring now to the figures, in particular to FIGS. 1A through 1E and1G, there is shown an exemplary over-the-road trailer 1 with an enclosedcargo holding area 1 a. On the back end of the trailer 1, a left handapparatus 2 and a right hand apparatus 3 are mounted and shown invarious configurations. FIGS. 1F, 1H, and 1I show the right handapparatus in detail in various configurations including a rear door 9 ofthe trailer 1 which, in this embodiment, serves as a mounting platformfor the right hand apparatus 3 and is also part of the apparatus 3. Theleft hand apparatus 2 is a mirror image of the right hand apparatus 3.For gaining access to the cargo holding area 1 a of the trailer 1, theapparatuses 2 and 3 are opened as typical trailer doors.

If the apparatuses 2 and 3 are symmetric in a vertical direction, asthey are shown here, they can be identical with each other. In thiscase, the apparatuses 2 and 3 are simply assembled to the trailer 1upside down from each other.

There are trailers and other vehicles that neither have rear doors norneed access to the rear of the vehicle. For these applications, theapparatuses 2 and 3 could be combined together, joined at their commonedges. This would result in fewer parts and less weight.

FIGS. 1F, 1H, and 1I reveal other features of a typical apparatus 2 or 3in addition to the door/mounting platform 9. In this section of thedisclosure, the placement position of the features and components isdescribed with respect to a fully deployed apparatus as shown in FIG.1I. Immediately behind and fixedly connected to the door/mountingplatform 9 are an optional extension-retraction system 10 and the firstpanel assembly 5. A plurality of intermediate panel assemblies 6, eachhaving a different size but sharing the same features, follows the firstpanel assembly 5. The last panel assembly 7 immediately follows the lastintermediate panel assembly 6. Connecting the various panel assemblies5, 6, and 7 to each other are sets of extension-retraction linkageassemblies 4 or 8. Linkage assemblies 4 and 8 perform the same function,but linkage assembly 8 is narrower in the direction of its pivot axisand is used between the rearward panel assemblies 6 and 7 where there isless available space.

A set of extension-retraction linkage assemblies 4 or 8 holds eachintermediate panel assembly 6 to the panel assembly 5 or 6 immediatelyin front of it. A second set of linkage assemblies 4 or 8 holds eachintermediate panel assembly 6 to the panel assembly 6 or 7 immediatelyto its rear. In this way, all panel assemblies 5, 6, and 7 are held toeach other in series with a set of linkage assemblies 4 or 8 betweeneach. The linkage assemblies 4 or 8 in each set allow linear movementbetween each panel assembly 5, 6, or 7 and its neighbor(s). Toaccomplish the linear movement, at least two linkage assemblies 4 or 8are required in each set. Each linkage assembly 4 or 8 by itselfconstrains the panel assembly 6 or 7 connected to its rear to move in aplane perpendicular to its joint axes of rotation. If two linkageassemblies 4 or 8 have corresponding axes that are collinear, the panelassembly 6 or 7 is still constrained to move in a perpendicular plane.However, if the corresponding axes are coplanar, but not collinear, asecond planar constraint is formed. In this case, the two planarconstraints combine to form a linear constraint at their commonintersection. This is the method the present invention employs.Additional linkage assemblies 4 or 8 may be used to distribute the loadstransferred between panel assemblies 5, 6, or 7 among more connectionlocations.

Referring to FIGS. 2A through 2H, the extension-retraction linkageassembly 4 and its components and features are shown. The linkageassembly 4 consists of two links 11 and 12 that rotatably connect toeach other with the cylindrical surface 16 of link 11 forming a jointwith the cylindrical surface 18 of link 12. This joint is constrainedsuch that it effectively rotates about the common centerlines of theabove surfaces. Provisions are made that effectively restrict any linearmovement along the common centerlines. A torsional spring 13 is alsoincluded along the above joint that tends to cause the cylindricalsurfaces 14 and 20 at the ends of the linkage assembly 4 to extend awayfrom each other. To keep the linkage assembly 4 from overextending, astop 17 is provided on link 11 that contacts a surface 21 on link 12.Unless an external force is acting on the linkage assembly 4, the spring13 keeps the stop 17 and stop surface 21 in contact with each other witha certain amount of preload. The various features of link 11 are held inplace by one or more link arms 15. The various features of link 12 areheld together by one or more link arms 19. When assembled, thecenterlines of the cylindrical surfaces 14, 16, 18, and 20 are allparallel with each other.

The extension-retraction linkage assembly 4 also connects to the variouspanel assemblies 5, 6, and 7 as mentioned above and described below.Panel assemblies 5 and 6 have interior cylindrical surfaces 23 and 24that rotatably connect to cylindrical surface 14 of link 11. Likewise,panel assemblies 6 and 7 have cylindrical surfaces 26 and 27 towardstheir upstream edge that rotatably connect to cylindrical surface 20 oflink 12. As shown in FIGS. 3A through 3C, 3E, and 3F, the centerlines ofsurfaces 23 and 24 are coplanar, but not collinear. Likewise, as shownin FIGS. 3B through 3F, the centerlines of 26 and 27 are coplanar, butnot collinear. This geometry satisfies the above requirement to producelinear movement between adjacent panel assemblies 5, 6, and 7 when usedwith two or more linkage assemblies 4 or 8 as described above.

The panel assemblies 5, 6, and 7 are each constructed from a set ofpanels 22 that also locate the various features described above. Notches29 are cut into the upstream edge of the panels 22 as required toprovide clearance with the linkage assemblies 4 and 8 as they travelthrough their range of motion.

There are other benefits provided by the linkage assemblies 4 or 8 andpanel assemblies 5, 6, and 7 when used together as described above. Oneis the travel-stop function that keeps the panel assemblies 5, 6, and 7from over retracting and over extending. FIG. 5 illustrates this byshowing two linkage assemblies 4 extended against their respective stops17. The pair of panel assemblies 6 shown higher in the figure is fullyextended and is prevented from extending farther by the stop 17 on thelinkage assembly 4. Likewise, the lower pair of panel assemblies 6 arefully retracted and prevented from retracting farther by the stop 17. Asecond benefit is the self-return function. When each linkage assembly 4or 8 is spring loaded against its stop 17, each pair of panel assemblies5, 6, and 7 connected to them has only two stable positions—fullyextended and fully retracted. If the pair of panel assemblies 5, 6, and7 are put in another configuration and released, the spring 13 willreturn the pair to one of the two stable positions. This feature allowsthe apparatuses 2 and 3 to be set in an extended or retractedconfiguration and keep this position until the opposite configuration isdesired.

If desired, an optional feature can be incorporated on the apparatuses 2and 3 that allows for remote, powered extension and retraction. FIGS. 4Athrough 4C illustrate this extension-retraction system 10 as applied tothe current form. FIG. 14K also illustrates this extension-retractionsystem as applied to a similar form. The larger scale of FIG. 14K showsthe routing of the extension-retraction web 10 a more clearly. FIG. 3Fshows a typical panel assembly 6 cross-section and highlights the webrouting features 25 and 28. To operate the extension-retraction system10, a drive motor 32 rotates a connected drive pulley 33, which moves aweb 10 a in one direction when turning clockwise and the oppositedirection when turning counter-clockwise. As shown, the web is keptunder tension by a pair of tensioning pulleys 35 which also serve tokeep most of the drive pulley 33 in contact with the web 10 a. A corneridler pulley 34 is also employed near the joint between the first panelassembly 5 and the trailer door/mounting platform 9. The web 10 a isattached on each end to the last panel assembly 7. One end is attachedat a downstream connection point 31, and the opposite end is attached atan upstream connection point 30.

The operation of the extension-retraction system 10 is described below.If retraction is desired, the drive motor 32 is made to turncounter-clockwise as shown in FIG. 4B. This causes a tension increase inthe section of web 10 a between the drive motor pulley 33 and webconnection point 31. The increase in tension pulls the last panelassembly 7 towards the first panel assembly 5. Since the panelassemblies 5, 6, and 7 and linkage assemblies 4 and 8 are connected inseries, the entire linkage-panel chain feels a force pulling it towardsthe first panel assembly 5. At a certain point as the tension forceincreases, the spring 13 preload forces in a certain set of linkageassemblies 4 or 8 are overcome. This causes the pair of panel assemblies5, 6, or 7 on either side of the overcome set of linkage assemblies 4 or8 to switch to a retracted configuration. As the drive motor 32continues to turn, the panel assemblies 5, 6, and 7 each switch to aretracted configuration until the entire apparatus 2 or 3 is in theretracted configuration. With certain options described below, it may bedesirable to have the panels retract in a predetermined sequence. Toaccomplish this, the linkage preload springs 13 may be customized foreach linkage assembly 4 or 8 set putting weaker springs on those setsthat are desired to retract first and stronger springs on those setsthat are desired to retract last.

If it is desired to extend the apparatus 2 and 3, the drive motor 32 ismade to turn clockwise as shown in FIG. 4B. This causes a tensionincrease in the section of web 10 a between the drive motor pulley 33and the web connection point 30. The increase in web 10 a tensionbetween web routing features 25 and 28 on the same panel assembly 6 isreacted by internal stresses within the panel assembly 6. The increasein web tension between panel assemblies 5, 6 and 7 results in a forcepulling the upstream edge of the downstream panel assembly 6 or 7 towardthe downstream edge of the upstream panel assembly. This force isinitially resisted by the spring 13 preload force in the linkageassemblies 4 and 8. At a certain point as the tension force increases,the spring 13 preload force in a certain set of linkage assemblies 4 or8 is overcome. This causes the pair of panel assemblies 5, 6, or 7 oneither side of the overcome set of linkage assemblies 4 or 8 to switchto an extended configuration. As the drive motor 32 continues to turn,the panel assemblies 5, 6, and 7 each switch to an extendedconfiguration until the entire apparatus 2 or 3 is in the extendedconfiguration.

A benefit of the extension-retraction system 10 as described above isthat the routing length of the web 10 a remains nominally the sameregardless of the configuration of the panel assemblies. This avoids theneed for a web 10 a take up and storage system.

If a larger radius on the web guiding features 25 and 28 within thepanel assemblies 5 and 6 is required, either the panel assembly can bemade thicker or the features 25 and 28 could be made to protrude outsidethe existing panel assembly 5 and 6 boundary. The protrusion couldeither be covered or left open to the environment. This will likelycause a small increase in drag, but may render the present inventionmore robust.

A space is reserved for the extension-retraction motor 32, drive pulley33, tensioning pulleys 35, and related mounting hardware by making thelast panel assembly 7 shorter in depth than the other panel assemblies 5and 6. When retracted, the last panel assembly 7 is positioned to therear of the drive motor 32, but remains within the overall contours ofthe retracted apparatus 2 and 3. In the case that theextension-retraction system 10 is not used, or in the case that the formof the invention provides a space for the motor 32 and its related itemsto occupy (as with apparatuses 40, 41, and 72), the panel assemblies 5,6, and 7 should be the same depth to minimize the volume required in theretracted configuration.

Each apparatus may require its own extension-retraction system 10. Itwould also be possible for one apparatus 2 or 3 to drive the otherapparatus 2 or 3. This could be done by forming some type of connectionsuch as pins and pinholes across the halves. These connections couldalso provide structural reinforcing from one half to the other.

As shown in FIGS. 7A and 7B, vortex generators 36 may be added to theexterior of certain panel assemblies 5, 6, and 7. Vortex generators 36are formed by adding a relatively small protrusion to the exteriorsurfaces. Their purpose is to add a small amount of turbulence to theairflow in their local area in the form of a small vortex. The goal ofadding turbulence is keeping the airflow attached over a larger area ofthe exterior of the apparatus 2 and 3. If the vortex generators 36 areadded sufficiently downstream on the panel assemblies 6 and 7, they willtuck inside the adjacent upstream panel assemblies 5 and 6 when theapparatuses 2 and 3 are retracted.

The descriptions above focused on a basic form and shape of the presentinvention and included certain optional features. The basic form aboveis thought to provide the lowest cost solution with acceptableperformance for over-the-road trailers 1 and also provide access to theenclosed trailer volume 1 a. Just as vehicles and trailers come invarious forms and are operated in many different environments with manydifferent requirements, there are also different adaptations of thepresent invention. Some of these will be discussed below.

There are known trailer skirts 39 that may be added to over-the-roadtrailers as shown in FIGS. 8A through 8D. These trailer skirts 39 couldbe combined with the present invention in the basic form described aboveand exemplified by apparatuses 2 and 3. However, a greater reduction inaerodynamic drag could be achieved by employing the trailer skirts 39 incombination with vertically lengthened apparatuses 37 and 38 as shown inFIGS. 8A through 8D. These apparatuses 37 and 38 differ from the basicapparatuses 2 and 3 only by an increase in the length of the verticalpanels 22. It may be desirable to add additional linkage assemblies 4 or8 along the length of these extended panels 22 to further distribute theload.

Upon testing, it may be found that significant airflow separation occurssomewhere along the length of the fully extended apparatuses 2 and 3.Testing may also reveal that there is little benefit provided byextending the apparatuses 2 and 3 until a vertex is formed, and theextra weight and cost is not worth the small benefit. Highwayregulations may also limit the maximum length of the vehicle of trailer.In these cases, it may be desirable to use a truncated form of theapparatuses 40 and 41 as shown in FIGS. 9A through 9D.

Upon testing, it may be found that better aerodynamic performance isgained by reducing the slope of one or more surfaces. This can beaccomplished by replacing the linkage assemblies 4 or 8 and relatedattachment points 23, 24, 26 and 27 and notches 29 with linear slidingjoints as shown in FIGS. 10A through 10G on apparatuses 42 and 43. Toaccomplish this, the panel assembly 44 is fitted with a key 45 and way46 that engage the key 45 and way 46 of adjacent panel assemblies 44.

In addition to over-the-road trailers 1, the present invention may beadapted to other vehicles. FIGS. 11A through 111 show a form suitablefor use behind a minivan 51. The left hand apparatus 52 and right handapparatus 53 have panel assemblies 55 and 56 of mixed shapes that allowthem to blend to the contours of the minivan 51. The panel assembly 56as shown in FIG. 11H transitions from one shape to another. The conceptof transitioning shapes across a panel assembly 56, as illustrated here,can also be applied to other forms of the invention. The onlylimitations to this are that the panel assemblies must nest within eachother when the apparatuses 52 and 53 are retracted, the mating edgesmust meet when the apparatuses 52 and 53 are deployed, and the linkageassemblies 4 or 8 must have adequate clearance over their required rangeof motion.

In the case of the minivan 51, shown in FIGS. 11A through 11C and 11F,the rear surfaces are not vertical and do not meet with the apparatuses52 and 53. To provide a smooth transition from the minivan to theapparatuses 52 and 53, an aerodynamic fairing 54 is employed.

In addition to vehicles that have blunt rear surfaces as describedabove, vehicles such as pickup trucks 61 may benefit from the presentinvention. Pickup trucks 61 typically have blunt rear facing surfacesbehind the passenger cab. As shown in FIGS. 12A through 12C, a form ofthe apparatus 62 may be employed. This form of the invention alsoemploys linear sliding joints with keys 45 and ways 46 as describedearlier on two surfaces of each panel assembly 65, 66, and 67 that areshown in detail in FIGS. 12E and 12G through 12I.

In this form, the linkage assembly 63 is optional. As shown in FIG. 12F,the linkage assembly 63 is comprised of two linkage assemblies 4 incombination with a straight shaft connection 64 between them. This isuseful to coordinate the motion of one or more linkage assemblies 4 thatare separated by a distance. This form of linkage assembly 63 may alsobe employed on other forms of the invention between two or more linkageassemblies 4 or 8 that have collinear joints axes. A flexible shaftconnection could be used in forms of the invention that havenon-collinear joints. A gear train connection could also be used tocoordinate movement between various linkage assemblies. The linkageassemblies could be between the same or different sets of panels. Anactuator could power one or more of these connected linkage assemblies.

If the linkage assembly 63 is used with apparatus 62, it could providethe benefits of a self-return function and a travel-stop function, asdescribed above.

In addition to vehicles that have predominately horizontal and verticalexterior surfaces as described above, the present invention may beadapted to vehicles with other shapes. FIGS. 13B through 13K show a formsuitable for use behind a tanker trailer 71 with an ellipticalcross-section. In this case, no access to the rear of the trailer 71 isrequired. Thus the apparatus 72 is made as a whole and not in halves.

The panel assemblies 75, 76, and 77 are made in the general shape of thetanker trailer 71. The panel assembly 77 farthest downstream in theextended configuration is formed with a smooth capping surface. Thelinkage assemblies 4 and 8 are used in sets of three. Correspondingly,three sets of linkage mounting surfaces 79 and 80 are provided to attachthe linkage assemblies 4 and 8. Shallow grooves 78 are cut into thepanel assemblies 75 and 76 to allow the linkage assemblies 4 or 8 tomove through their required range of motion.

To smooth the transition from the tanker trailer 71 to the apparatus 72,an aerodynamic fairing 73 is employed. The fairing 73 also covers adomed surface at the rear of the tanker trailer 71.

A modification to the basic form of the invention is shown in FIGS. 14Athrough 14K that provides for a smooth transition from the exteriorsurfaces of the over-the-road trailer 1 to the apparatuses 82 and 83.This form of the apparatuses 82 and 83 has all the same components andfeatures as the basic apparatuses 2 and 3 except for those specificallymentioned in the conversion process below. Apparatuses 82 and 83 willreduce drag, but will cost more to produce. To convert apparatuses 2 and3 into apparatuses 82 and 83, several steps are required. To begin, thefirst panel assembly 5 is replaced by the first panel assembly 85. Next,the panel assembly 6 adjacent to the first panel assembly 85 is replacedby panel assembly 86. Finally, the first set of linkage assemblies 4 arereplaced by a set of linkage assemblies 84, and the extension-retractioncorner pulley 34 is moved slightly. The first panel assembly 85 hascurved surfaces that blend the overall slope of the apparatuses 82 and83 with the trailer 1. This creates a slightly smaller space for theextension-retraction linkage assembly 84 to occupy. This is addressed byusing link 88 and link 89 in the linkage assembly 84, resulting in alower profile. A torsional spring 81 is used to spring load the linkageassembly 84 into the extended position. Panel assembly 86 differs frompanel assembly 6 only by small notches 87 that are required to allow thelinkage assembly 84 to operate through its range of motion.

Optional doors 90, 91, 92, and 93 may be added to the basic apparatuses2 and 3 as shown in FIGS. 15A through 15F. These doors serve twofunctions but add cost and complexity to the apparatuses 2 and 3. Thefirst function is keeping mud, snow, ice, and other debris out of theinterior of the apparatuses when they are in the retracted configurationby covering up the openings between the panel assemblies 5, 6, and 7 asshown in FIG. 15B. The second function is providing a smoothertransition across the panel assembly joints when in the extendedconfiguration as shown in FIG. 15D. The latter will reduce drag. Thedoors 90, 91, 92, and 93 are actuated by a spring-loaded hinge 94 thattends to rotate them to a closed position. As the apparatuses 2 and 3extend, the panel assemblies 6 and 7 simply overpower the spring-loadedhinges 94 and open the doors. The sequence that the panel assemblies 6and 7 open is important when the optional doors 90, 91, 92, and 93 arepresent. As illustrated in FIG. 15E, the upstream panel assemblies 6should extend sequentially before each downstream panel assembly 6 and 7to avoid having the tips of the doors 90 and 91 caught in the hinge areaof the doors 90 and 91 below it. As described above, this can beaccomplished by putting stiffer springs 13 on the downstream linkageassemblies 4 and 8.

A modification to the basic form of the invention is shown in FIGS. 16Athrough 16J that provides for a smooth transition from the exteriorsurfaces of the over-the-road trailer 1 to the apparatuses 102 and 103and between the panel assemblies 105 and 106 when fully extended. Thismodification consists of a pair of first panel assemblies 105 havingessentially the same form and features as the pair of first panelassemblies 85 described above. In addition, a set of linkage assemblies84 connects the first panel assemblies 105 to the corresponding panelassemblies 106. Furthermore, the exterior shape of panel assemblies 106is modified from panel assemblies 6. Doors 110 and 111 are added andserve a similar function to the doors 90, 91, 92, and 93 as described inthe preceding paragraph. Finally, corner covers 112 provide a smoothshape to the corners of the apparatuses 102 and 103 when fully extended.In this form, the invention will produce a greater drag reduction, butat a greater cost and complexity.

As shown in FIG. 16H, the doors 110 and 111 combine with the exteriorsurfaces of the panel assemblies 106 to form a smooth contour along theexterior of the apparatuses 102 and 103 when fully extended with theexception of the corners. The doors 110 and 111 are actuated in asimilar fashion to the doors 90, 91, 92, and 93 mentioned above.

The doors 110 and 111, in a fully extended configuration, do not reachthe corner of the apparatuses 102 and 103. This leaves a small portionof the corner uncovered similar to the corner shown in FIG. 15A. Cornercovers 112 can be attached to the doors 102 and 103 to cover the cornersin a smooth manner as shown in FIGS. 16K through 16M. The hinge 94between the corner covers 112 and the door 110 or 111 is spring-loadedand tends to return to the fully extended configuration. When theapparatuses 102 and 103 retract, the corner cover 112 pushes against theneighboring corner cover 112, and they both fold into the retractedconfiguration as shown in FIG. 16M. This results in the corner covers112 protruding the farthest downstream when the apparatuses 102 and 103are fully retracted. The corner covers 112 are optional, and FIGS. 16Gand 16J are shown without them.

Different methods may be employed to gain access to the rear of thevehicle or trailer. FIGS. 17A and 17B show hinges 118 connecting theapparatuses 2 and 3 to the trailer 1. This type of connection has beenimplied above.

FIGS. 18A and 18B show a telescoping linear slide 121 connecting theapparatuses 122 and 123 to the trailer 1. As shown in FIG. 18C, theapparatuses 122 and 123 differ from the basic apparatuses 2 and 3 onlybecause they have a linear slide feature 124 on them. The telescopinglinear slide 121 has trailer attachment points 125.

FIGS. 19A through 19G illustrate articulating links 127, 128, and 129that move the apparatuses 2 and 3 from a closed position as shown inFIGS. 19A and 19C, to a fully open position as shown in FIGS. 19B and19G.

A modification to the basic form of the invention is shown in FIGS. 20Athrough 20E that replaces the linkage assemblies 4 and 8 with straightlinks (or hinged panels) 133 and 134. The simplicity of the straightlinks 133 and 134 may result in a lower overall cost for this form ofthe invention compared to the basic form, exemplified by apparatuses 2and 3. However, the reduced cost sacrifices the robust travel-stopfunction as described above. The door/mounting platform 131 isessentially the same as the door/mounting platform 9 described above.The panel assemblies 132 and 135 replace panel assemblies 6 and 5respectively. The panel assemblies 132 and 135 have significantlysmaller pivoting surfaces 23, 24, 26, and 27 in a slightly differentlocation. The notches 29 are removed from panel assembly 132, which isinstead trimmed to a shorter depth than panel assembly 135. This allowsthe straight links 134 to sit in a gap upstream from the upstream edgeof the panel assemblies 132 when the apparatus is in the fully retractedconfiguration.

A modification to the basic form of the invention is shown in FIGS. 21Athrough 21O that provides for a smooth transition from the exteriorsurfaces of the over-the-road trailer 1 to the apparatuses 202 and 203and between panel assemblies, 201, 205, 206, and 207 when fullyextended. In the present form, a more gradual transition is possiblethan those described above in apparatuses 82, 83, 102, and 103. This ispossible because the transition occurs over two panel assemblies 201 and205. This concept could also be used to extend the transition over threeor more panel assemblies.

When making a gradual transition over multiple panel assemblies 201 and205, the panel assemblies 201 and 205 end up closer to each other in theretracted configuration as compared to the basic form in apparatuses 2and 3. At some point, a practical linkage assembly 4 will no longer fitbetween the panel assemblies 201 and 205. The present form of theinvention resolves this problem by using linkage assemblies 204 and 208of a different form to connect the first three panel assemblies 205,201, and 206. These linkage assemblies 204 and 208 fit in front of thepanel assemblies 201 and 206 when the apparatuses 202 and 203 are fullyretracted as shown in FIGS. 21M and 21N. To conserve space, linkageassembly 208 nests inside of linkage assembly 204. This concept could beextended to three or more linkage assemblies as well.

Linkage assemblies 204 connect to the first panel assembly 205 near itsupstream edge at pivot points 234 and 235. On the other end, linkageassemblies 204 connect to the second panel assembly 201 near itsupstream edge at pivot points 236 and 237. Pivot points 236 and 237 arealso used by linkage assemblies 208 to connect the second panel assembly201 to the third panel assembly 206 near its upstream edge at pivotpoints 26 and 27. This results in the second panel assembly 201 notbeing in the linkage chain, but merely attaching to linkage pivotpoints.

The panel assemblies 206 and 207 downstream from the gradual transitionarea retain the same pivot features 23, 24, 26, and 27 as the panelassemblies 6, 7, 56, 86, and 106 used in the apparatuses 2, 3, 52, 53,82, 83, 102 previously described. Likewise, linkage assemblies 4 areused in conjunction with these downstream panel assemblies 206 and 207.

As shown in FIGS. 22A through 22E, the linkage assemblies 204 and 208use a stop pocket 223 and stop protrusion 224 to prevent over travel.The stop pockets 223 are placed in links 221 and 225 and the stopprotrusions 224 are placed in links 222 and 226. In addition to thetravel stop function, the stop pocket 223 and stop protrusion 224together perform a detent function. This is done by having the stoppocket 223 deeper at the end of the travel range. The stop protrusions224 are spring-loaded and thus move into these detents. The result isthat the apparatuses 202 and 203 are stable in the fully retracted andfully extended configuration.

The present form of the invention incorporates vertical covers 210 andhorizontal covers 211 in much the same way as apparatuses 102 and 103.They serve the function of keeping debris out of the apparatuses 202 and203 when they are in the closed configuration. When in the extendedconfiguration, the covers smooth the transition between panel assemblies201, 205, 206, and 207.

Corner covers 212 are also used in the present form of the invention.These corner covers 212 have a single hinge line 94 connecting them tothe corresponding panel assemblies 201, 205, and 206. The primaryfunction of the corner covers 212 is to form a smooth surface near thecorners when the apparatuses 202 and 203 are fully extended.

To assist in keeping the panel assemblies 201, 205, 206, and 207properly aligned with each other when the apparatuses 202 and 203 arefully extended, optional guides 220 are incorporated along the leadingedge of the panel assemblies 201, 206, and 207. These guides contact theinside surfaces of the downstream edge of the panel assemblies 205, 201,and 206 immediately upstream. The trailer door 209 accommodates theguides 220 belonging to the second and third panel assemblies 201 and206 with appropriate pockets.

An alternative to the linkage assemblies 204 and 208 would be to uselinear slides 45 and 46 as shown in FIGS. 10E, 10F, and 10G.

An alternative form of the present invention is illustrated in FIGS. 24Athrough 24D, FIGS. 25A through 25D, FIGS. 26A through 26F, and FIGS. 27Athrough 27J. In the present form, one or more of the panel assemblies 5,6, 7, 44, 55, 56, 65, 66, 67, 75, 76, 77, 85, 86, 105, 106, 132, 135,201, 205, 206, and 207 belonging to a previous form of the invention arereplaced by a corresponding framework 305 and 306. The framework 305 and306 retains the attachment points 23, 24, 26, 27, 79, 80, 234, 235, 236,and 237 connecting to the linkage assemblies 4, 8, 63, 84, 204, and 208.The function and operation of the linkage assemblies remain the same asin the previous corresponding form. Likewise, the optionalextension-retraction system 10 is retained by the present form,including web routing features 25 and 28 and web connecting features 30and 31. To provide an aerodynamic surface, fabric 308 is connected tothe framework 305 and 306 and, in some cases, to panel assemblies 304and 307.

An example of the present form of the invention (excluding the fabric308) is shown in FIG. 24A fully extended and attached to the rear of anover-the-road trailer 1. If the fabric 308 were included in this view,the appearance and exterior shape would be similar to that of FIG. 21A.As in earlier forms, this exemplary form has the aerodynamic dragreducing apparatus split in two halves, right 303 and left 302.

The fabric 308 attaches to the framework 305 and 306 at the trailingedge. When fully extended, the framework 305 and 306 provide shape andsupport to the fabric. When partially extended and when fully retracted,the fabric 308 takes the form of a bellows as shown in FIGS. 26A and26D, FIGS. 27A through 27C, and FIGS. 27F through 27H.

Optionally, it may be desired to have the fabric 308 drawn into thespaces in between the frameworks 305 and 306 and panel assemblies 304and 307 as shown in FIGS. 26A and 26D. In this case, elastic members canbe attached between various points on the fabric 308 and the frameworks305 and 306 and panel assemblies 304 and 307. When fully extended, theelastic members are overcome by the extension forces and the bellowsshape is lost. An alternative method would be to embed elastic membersinto the fabric 308. In this case, the fabric 308 would take a bellowsshape when no external loads were present. An additional alternativemethod would be to attach the fabric farther upstream than the trailingedge of the framework.

The fabric 308 serves several potential functions. The first is toprovide all or part of the aerodynamic surface when the apparatus isfully extended. A second function is to carry tensile and shear loadswhen the apparatus 302 and 303 is fully extended. A third is to protectthe joints of the linkage assemblies from the elements. A fourth is toprovide an optional means for extending and retracting the apparatus.This is done by the fabric 308 serving as a bladder. To extend theapparatus 302 and 303, this bladder is filled with air. To retract thebladder, the air is evacuated.

The fabric 308 may be airtight or it may be porous. The fabric may bestiff or it may be stretchable.

In the present disclosure, the words “a” or “an” are to be taken toinclude both the singular and the plural. Conversely, any references toplural items shall, where appropriate, include the singular.

In the present disclosure, many features are described with respect tothe theoretical design. For instance, “completely smooth” refers to thetheoretical design shape. It is understood that imperfections exist andclearances are required in real parts. In these cases, such terms areused to distinguish the differences between theoretical designs.

It is desirable for drag reducing devices in accordance with theprinciples of the present disclosure to be shaped to reduce the effectsof air flow separation. In certain example embodiments, drag reducingdevices in accordance with the principles of the present disclosure maydefine an angle θ (see FIG. 21F) relative to the rear surface of thevehicle that is less than 18 degrees, or in the range of 10 to 18degrees. As the drag reducing devices extend in a rearward directionrelative to the vehicle, the drag reducing devices may be straight asshown at FIG. 1I. Alternatively, the drag reducing devices may includeat least portions having segments angled relative to one another atprogressively steeper angles as the devices extend in a rearwarddirection. In still other embodiments, at least portions of the dragreducing devices may curve as the devices extend rearwardly from theircorresponding vehicles. In still other embodiments, the drag reducingdevices may curve continuously along their lengths. Angle variations(e.g., curves or angled segments as described above) can be used toprovide smooth transitions from the rear of the vehicle to the mainbodies of the drag reducing devices.

When extended, drag reducing devices in accordance with the presentdisclosure may define relatively discrete peaks (see FIG. 1A) or may betruncated (see FIG. 21E). In certain truncated embodiments, the extendedlengths of the drag reducing devices are such that the effects of dragcaused by air separation at the truncated ends are minimal. In exampleembodiments suitable for tractor trailers, the drag reducing devices mayhave extended lengths greater than 6 feet, or in the range of 6 to 22feet, or in the range of 8-14 feet. Vehicles having smaller heights andwidths could be equipped with proportionally smaller drag reductiondevices. In certain embodiments, the ratio of the extended length of thedrag reduction device to a reference dimension of the vehicle is atleast 1 to 1. The reference dimension is typically the smaller of thewidth or the height of the rear of the vehicle body. In the embodimentof FIG. 21A, the width w is the reference dimension since it is smallerthan the height h. In other embodiments, this ratio is at least 1.5 to1, or at least 2 to 1, or at least 3 to 1.

In certain embodiments, drag reducing devices in accordance with thepresent disclosure may be automatically extended or retracted. A controlsystem may be used to automatically control extension and retraction. Incertain embodiments, vehicle speed or other vehicle parameters may beused to automatically control retraction/extension. For example, acontroller may sense vehicle speed, and automatically cause retractionof the drag reducing device if the vehicle speed moves below a givenspeed value (e.g., 45 miles per hour).

Retractable drag reducing devices in accordance with the presentdisclosure can have relatively long extended lengths as compared toretracted lengths. Certain embodiments have an extended length toretracted length ratio of at least 6 to 1. Other embodiments haveextended length to retracted length ratios of at least 10 to 1 or atleast 20 to 1.

While specific angles and lengths have been specified for certainembodiments of the present disclosure, it will be appreciated that thebroad aspects of the present disclosure are not limited to these values.

From the foregoing it will be observed that numerous modifications andvariations can be effectuated without departing from the true spirit andscope of the novel concepts of the present invention. It is to beunderstood that no limitation with respect to the specific embodimentsillustrated is intended or should be inferred.

What is claimed is:
 1. A drag reducing device for use in reducing dragon vehicles, the drag reducing device comprising: a drag reducingassembly that is movable between an extended configuration and aretracted configuration, the drag reducing assembly including a firstend adapted for connection to the vehicle and a second end that is movedoutwardly from the first end when the drag reducing assembly is movedfrom the retracted configuration toward the extended configuration; aflexible member routed through the drag reducing assembly; a motor formoving the flexible member in first and second directions, the flexiblemember causing the drag reduction assembly to extend when moved in thefirst direction, and the flexible member causing the drag reductionassembly to retract when moved in the second direction; and a set oflinkages that interconnect the first end to the second end; wherein atensile load is transferred through the flexible member to move the dragreducing assembly from the extended configuration to the retractedconfiguration, and wherein another tensile load is also transferredthrough the flexible member to move the drag reducing assembly from theretracted configuration to the extended configuration.